Microsoft 365 MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond annotations (readOnlyHint), the description adds valuable behavioral context: it specifies retrieval can return 'properties, relationships, or raw contents' (distinguishing metadata vs binary content) and clarifies polymorphic attachment targets (events, messages, posts).

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

First sentence is efficient and front-loaded with key information. Second sentence contains a dangling colon ('following types:') suggesting missing enumerated content, wasting space without adding value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers polymorphic attachment targets and hints at return types (properties vs raw contents), but lacks output schema documentation and guidance on parameter dependencies (messageId/attachmentId hierarchy) given the complexity of 7 parameters.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 100% schema description coverage, baseline is 3. The description mentions 'properties' and 'relationships' which loosely maps to select/expand parameters but does not add specific semantics for individual parameters like fetchAllPages or the hierarchical relationship between messageId and attachmentId.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Clear specific verb (Read) and resource (attachment) with scope clarification (attached to user event, message, or group post). Distinguishes from mutation siblings (add/delete) by stating read-only intent, though could more explicitly contrast with list-mail-attachments.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance on when to use this specific tool versus alternatives. It never states that you need specific messageId/attachmentId values (likely obtained from list-mail-attachments or get-mail-message) nor when to prefer this over listing operations.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.